<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			/*
			兄弟间margin合并，取较大的正值
			*/
			div{
				height: 100px;
				width: 100px;
				background-color: #00FFFF;
			}
			.bro_1{
				margin-bottom: 100px;
			}
			.bro_2{
				margin-top: 200px;
			}
		</style>
	</head>
	<body>
		<div class="bro_1"></div>
		<div class="bro_2"></div>
	</body>
</html>
